As Other Death Rates Fall, Cancer's Scarcely Moves

By GINA KOLATA

Published: April 24, 2009

Data from the National Center for Health Statistics show that death rates over the past 60 years -- the number of deaths adjusted for the age and size of the population -- plummeted for heart disease, stroke, and influenza and pneumonia. But for cancer, they barely budged.

The cancer death rate, now about 200 deaths a year per 100,000 people of all ages and 1,000 deaths per 100,000 people over age 65 -- is nearly the same now as it was in 1950, dropping only 5 percent. But the death rate from heart disease is only a third of what it was in 1950. Even though more people die of heart disease than from cancer, cancer deaths have been edging closer to heart disease deaths each year.

Are the statistics lying, hiding major advances because of the way the data are analyzed?

No, researchers say.

Death rates are not perfect -- no measure is. But they are considered the purest measure. That is one reason groups like the American Cancer Society and the National Cancer Institute use death rates rather than something else, like the number of people living with cancer, to assess progress in fighting the disease.

With heart disease, says Dr. Michael S. Lauer, director of the division of prevention and population sciences at the National Heart, Lung, and Blood Institute, there were transforming discoveries in prevention and treatment. They led to effective drugs to lower cholesterol and blood pressure, to the use of aspirin, and to smoking cessation programs, all of which reduced the number of heart attacks. And they led to treatments during and after a heart attack, like medical therapies, stents and bypass surgery, as well as powerful drugs to prevent and break down blood clots.

All these strategies contributed to the falling death rates. ''Fifty years ago, these either didn't exist or were in their infancy,'' Dr. Lauer said

But with cancer, equivalent transforming advances have not emerged.

Could there be other explanations for the stagnant cancer death rates? Not really, researchers say.

For example, there is the competing cause-of-death hypothesis. In the past, you died of a heart attack. Now, spared that, many live long enough to die of cancer. Wouldn't that mean cancer death rates look worse than they really are?

''No,'' says Dr. H. Gilbert Welch, a cancer epidemiologist at the Dartmouth Institute for Health Policy and Clinical Practice. He explains that the population of the United States is older than it was in 1950, but statisticians correct for that. They divide the population into discrete age groups, like 50 to 54, 55 to 59, and so on, and calculate death rates within each group.

So, suppose, for example, that in 1950, among 1,000 people aged 60 to 65, 10 died of cancer; that age group's cancer mortality rate, then, would be 10 per 1,000. Now, suppose that in 2009, because fewer people die of heart disease, twice as many live to be 60 to 65. If there had been no progress in combating cancer, you would expect that, with twice as many people in that age group, twice as many would die of cancer.

And that is pretty much what has happened.

But cancer is diagnosed in more people these days. If nearly the same number are dying from cancer -- adjusted for the age and size of the population -- wouldn't that mean that more are being cured, so the cancer death rate is lower?

Not really, says Donald A. Berry, head of the division of quantitative sciences at the M.D. Anderson Cancer Center in Houston. Death rates reflect deaths from cancer, not diagnoses. People living with cancer are part of the general population.

The additional diagnoses mostly result from more screening, Dr. Berry adds. While finding some cancers earlier may save lives, many would never have caused problems if they had been left alone. Others are deadly whether they are treated or not. Since there usually is no good way to decide whether a cancer will be deadly, doctors usually treat all as if they are life-threatening.

A result is an increase in diagnoses and survivors but, if treatment does not improve for deadly cancers, little change in the death rate.